Sealing means

ABSTRACT

Method and device for sealing a continuous product, such as an electrical cable, passing between zones at different pressures during manufacture wherein a liquid such as water, is used to effect sealing, and turbulence is created in the liquid to reduce the dimensions of the seal, e.g. by passing a suitable gas or gas mixture, such as air, through the liquid. The device may be a tube through which the product passes and in which the liquid forms a seal between the product and the tube wall. The gas may pass through suitably directed holes in the tube wall into the liquid. The gas may be directed against the flow of the liquid or may impart a spiral motion to the liquid. The spiral motion may also be produced e.g. by means of spring inserts in the tube.

United States Patent Newell 51 Aug.22,1972

[54] SEALING MEANS Filed: April 28, 1970 Appl. No.: 32,633

[30] Foreign Application Priority Data May 6, 1969 Great Britain ..23,003/69 US. Cl ..277/1, 277/70, 277/DIG. l,

285/10 Int. Cl. ..Fl6j 15/14, Fl6j 15/40 Field of Search.....277/135 J, 135, 70, 1; 285/10 References Cited UNITED STATES PATENTS 11/1960 Great Britain ..277/135J L 636,301 4/1950 Great Britain ..277/ 135 J 670,938 4/1952 Great Britain ..277/135 J Primary Examiner-Samuel B. Rothberg Attorney-Beveridge & De Grandi ABSTRACT Method and device for sealing a continuous product, such as an electrical cable, passing between zones at different pressures during manufacture wherein a liquid such as water, is used to effect sealing, and turbulence is created in the liquid to reduce the dimensions of the seal, e.g. by passing a suitable gas or gas mixture, such as air, through the liquid. The device may be a tube through which the product passes and in which the liquid forms a seal between the product and the tube wall. The gas may pass through suitably directed holes in the tube wall into the liquid. The gas may be directed against the flow of the liquid or may impart a spiral motion to the liquid. The spiral motion may also be produced e.g. by means of spring inserts in the tube.

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INVENTOR;

' WILLIAM GEORGE- NEWELL BY This invention relates to sealing means. It is particularly concerned with sealing means through which a processed or partially processed product is transferred from a first zone at a predetermined pressure to a second zone at a pressure different from that in the first zone, the pressure difference between the zones being maintained by the sealing means.

In passing any continuousv product into or out of a pressure vessel as part of the processing, it is necessary to pass the product through a sealing device. As an example, electrical cable when being cured in a steam tube has to pass out through a water cooling and sealing section. A common form of seal in the above example is a labyrinth seal embodying a series of close tolerance diaphragms or cones at each of which a pressure drop occurs. This form of seal is quite complicated in construction and usually embodies a large number of parts.

According to the present invention, the sealing means comprises a liquid seal and turbulence is created in the liquid to reduce the dimensions of the seal required to achieve the desired effect.

Conveniently, the liquid may be water, and the turbulence may be created by passing through the liquid a gas or gas mixture compatible with the liquid. A convenient gas mixture for use with water is air.

The sealing means may take the form of a tube or like hollow member through which the product passes, the liquid providing a seal between the product and the tube wall. Since there is a pressure difference between the ends of the tube, there will be some flow of liquid through the tube. For convenience, the liquid flowing through the tube may be recirculated.

The creation of turbulence, for example by aeration of water in the tube, increases the frictional drag per unit length on the water flowing through the tube. This increase results in an increase in the pressure gradient in the tube for a given rate of flow and therefore reduces the length of the tube needed to achieve a given pressure drop. With moderate clearance between the product (for example electrical cable) and the tube, the rate of flow is low. For a given tube and cable,v

the pressure gradient will be fixed.

Bores may be located in the tube to facilitate the creation of turbulence by passing air through them into the water. The bores may be disposed so that the air is directed against the pressure of the water and/or they may be tangentially disposed to impart a spiral path to the water when air is injected through them. Where high pressures are involved, the tube may be rifled or, more simply, provided with spring inserts to convert the potential energy of the water into spiral motion.

The spiral path of the water increases the efl'ective length of the tube. Increasing the path of the water for a given length of tube gives an increased pressure gradient. Turbulence may be increased by changing the direction of the spiral path. This may be achieved by having more than one set of tangential bores along the length of the tube, the bores of successive sets being oppositely disposed; or by using oppositely spiralled spring inserts. In this way the pressure gradient may be further increased. Change of the direction of spiralling of the water also avoids undue twisting of the products.

Where the product is electrical cable, the flow of water through the tube is needed for lubrication of the cable as it passes through the tube. The flow rate should be kept within reasonable limits but the pressure gradient should be as large as possible for a given rate of flow.

The invention includes both a method of maintaining a pressure difference between zones at different pressures during transfer of the product from one zone to the other as well as the sealing means for maintaining the pressure difference.

The invention will now be further described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is an end view of a sealing device;

FIG. 2 is a section taken on the line 2-2 of FIG. 1;

FIG. 3 is transverse section of the tube shown in FIG. 2;

FIG. 4 is a section taken on the line 4--4 of FIG. 3;

FIG. 5 is a section taken on the line 5-5 of FIG; 3; and

FIG. 6 is a fragmentary section corresponding to FIG. 2 of a modified form of the sealing device shown in FIGS. 1 to 5.

In the drawings, like numbers refer to like parts.

The sealing device shown in the drawings, has been designed to be simple in constructions, easily stripped and assembled and with only one essential interchangeable part the tube this being long lasting and easily made for any difierent size of product. In addition small clearances on the product are not necessary thus allowing adequate sealing on a product of wider dimensional tolerance.

The sealing device of FIGS. 1 to 5 was designed to be used with a pressurized fluid bed. Suitably this sealing device may be used with a water pressure of 60 p.s.i.g. and an air supply pressure of p.s.i.g. However, using higher air pressures and different dimensions higher water pressures could be held using the same principle. The arrangement of FIG. 6 is intended for use with higher pressures.

Referring to FIGS. 1 to 5, water under pressure is contained in a pipe 11 which is connected to a seal body 12 and this in turn is connected to an outlet pipe 13 by quick release clamps 14. Leakage from these three parts is prevented at the connection faces by O ring type seals 15.

A tube 16 is inserted into the seal body 12 as a push in fit from the high pressure side and is restrained by a small shoulder 17 on the insert at the high pressure end. Water or air leakage is again prevented at the connecting faces by O ring type seals 15.

The tube 16 26 has a bore drilled axially through it, the bore being bigger than the highest tolerance size of the cable 18 passing through it. Radial clearance of 0.045 inch on a 0.5 inch diameter cable can be tolerated quite easily, this being a sufficiently loose fit to permit easy threading of the cable. Due to this large clearance and because the bore is smooth right through the tube 16 and also because the water passing out through the seal from pipe 11 to pipe 13 acts as a lubricant, there is little or no abrasion on the product cable 18.

The tube 16 has also four l/l6 inch diameter holes 19 drilled radially through it and angled against the direction of water flow. In addition there are four more l/l6 inch holes 20 drilled so as to enter the bore tan- 3 gentially, these being in pairs at two points along the length of the tube.

In larger units for higher pressures there may be more holes drilled tangentially along the length of the tube 16. In some cases it is better to have the direction of these holes opposite as shown in FIGS. 4 and 5.

Air under a pressure greater than the water pressure is passed via an inlet 21 into the body of the seal 12 from where it passes through the small l/ 16 inch holes The water flowing out of the seal into pipe 13 is allowed to flow into a collecting tank (not shown) from where it may be re-pumped back into pipe ll'under pressure.

Referring to FIG. 6, the bore of the tube 16 is enlargedthroughout most of its length to accommodate oppositely spiralled spring inserts 22, 23 but is left with its normal diameter at the low pressure end of the tube ;to' provide an abutment 24 for the spring inserts. The

spring inserts 22, 23 replace the tangential bores of FIGS. 1 to 5 and impart spiral motion to the water passing down the bore of the tube 16, the direction of this spiral motion being reversed on passing from spring insert 22 to spring insert 23. The sealing member of FIG. 6 otherwise functions as that of FIGS. 1 to 5.

An example of the use of the sealing means shown in the drawings, will be briefly described, In this example, the sealing means or body 12 is inclined to the horizontal so that the tube 11 slopes upwardly and serves as a reservoir for the sealing liquid. The upper end of the tube 11 is connected to the outlet of a heated fluidized bed through which the cable 18 passes for curing purposes. On leaving the fluidized bed he cable passes down the tube 11 to the tube 16. Part way down the tube 11, the cable passes beneath the level of the liquid in the tube 11. From the tube 13, liquid leaving the tube 16 is recirculated to the upper end of the tube 1 1, via piping, by means of a pump.

Iclaim: I I

l. A method of maintaining a pressure difference between zones at-different pressures during transfer of a continuous product from one of said zones to the other, which comprises transferring the continuous product from a first zone at a predetermined pressure to a second zone at'a pressure different from that in the first zone through a confined space in which the product is sealed by a liquid flowing through said confined space due to the difference in pressure between the first zone and the second zone, and creating turbulence in the liquid to increase the pressure drop across the confined space by passing through the liquid a gas J or gas mixture which is compatible with said liquid.

2. A method as claimed in claim 1 in which the liquid is water.

'3. A method as claimed in claim 1 in which the liquid fl'thuthfds"rld.,

1 r me t ofi as ri ed En cl i l ic h 2: liquid is caused to flow in a spiral path through the confined space to increase the pressure drop across said confined space.

5. A method as claimed in claim 1 m which the turbulence iscreated by passing through the liquid a gas or gas mixture compatible with the liquid.

6. A method as claimed in claim 5 in which the gas mixture is air.

7. A method as claimed in claim4 in which the gas orv gas mixture is directed against the flow of the liquid.

8. Apparatus for maintaining a pressure difl'erencev 7 between zones at different pressures during the transfer of a continuous product from one of said zones to the other comprising a hollow member for providing a passage for the product between the zones, means for 7 providing a liquid seal for said product insaid passage I which seal comprises a liquid flowing in said passage due to the difference in pressure between the first zone and second zone and means for creating turbulence in said liquidto increase the pressure drop across the hollow member.

9. Apparatus as claimed in claim 8 in which the hollow member is a tube. V i

10. Apparatus as claimed in claim 8 in which said means for providing a liquid seal includes a reservoir for liquid connected to said hollow member.

11. Apparatus as claimed in claim 8 inwhich said means for creating turbulence comprises passages for gas located in the wall of said hollow member.

12. Apparatus as claimed in claim 11 in which the passages are bores.

13. Apparatus as claimed in claim 11 in which a chamber for said gas surrounds the hollow member.

14. Apparatus as claimed in claim 11 in which the passages extend obliquely through the wall of the hollow member to direct the gas against the pressure of the liquid.

15. Apparatus as claimed in claim 11 in which the passages are tangentially disposed in the wall of the hollow member to impart a spiral motion to the liquid.

16. Apparatus as claimed in claim 15 in which means are provided to change the direction of said spiral motion.

17. Apparatus as'claimed in claim 8 in which the hol low member contains at least one spring insert to impart a spiral motion to the liquid;

18. Apparatus as claimed in claim 17in which means are provided to change the direction of the spiral motion. r 

1. A method of maintaining a pressure difference between zones at different pressures during transfer of a continuous product from one of said zones to the other, which comprises transferring the continuous product from a first zone at a predetermined pressure to a second zone at a pressure different from that in the first zone through a confined space in which the product is sealed by a liquid flowing through said confined space due to the difference in pressure between the first zone and the second zone, and creating turbulence in the liquid to increase the pressure drop across the confined space by passing through the liquid a gas or gas mixture which is compatible with said liquid.
 2. A method as claimed in claim 1 in which the liquid is water.
 3. A method as claimed in claim 1 in which the liquid flowing through the confined space is recirculated.
 4. A method as claimed in claim 1 in which the liquid is caused to flow in a spiral path through the confined space to increase the pressure drop across said confined space.
 5. A method as claimed in claim 1 in which the turbulence is created by passing through the liquid a gas or gas mixture compatible with the liquid.
 6. A method as claimed in claim 5 in which the gas mixture is air.
 7. A method as claimed in claim 4 in which the gas or gas mixture is directed against the flow of the liquid.
 8. Apparatus for maintaining a pressure difference between zones at different pressures during the transfer of a continuous product from one of said zones to the other cOmprising a hollow member for providing a passage for the product between the zones, means for providing a liquid seal for said product in said passage which seal comprises a liquid flowing in said passage due to the difference in pressure between the first zone and second zone and means for creating turbulence in said liquid to increase the pressure drop across the hollow member.
 9. Apparatus as claimed in claim 8 in which the hollow member is a tube.
 10. Apparatus as claimed in claim 8 in which said means for providing a liquid seal includes a reservoir for liquid connected to said hollow member.
 11. Apparatus as claimed in claim 8 in which said means for creating turbulence comprises passages for gas located in the wall of said hollow member.
 12. Apparatus as claimed in claim 11 in which the passages are bores.
 13. Apparatus as claimed in claim 11 in which a chamber for said gas surrounds the hollow member.
 14. Apparatus as claimed in claim 11 in which the passages extend obliquely through the wall of the hollow member to direct the gas against the pressure of the liquid.
 15. Apparatus as claimed in claim 11 in which the passages are tangentially disposed in the wall of the hollow member to impart a spiral motion to the liquid.
 16. Apparatus as claimed in claim 15 in which means are provided to change the direction of said spiral motion.
 17. Apparatus as claimed in claim 8 in which the hollow member contains at least one spring insert to impart a spiral motion to the liquid.
 18. Apparatus as claimed in claim 17 in which means are provided to change the direction of the spiral motion. 